An overrated self-help movement started by frustrated 30 year old virgins turned amateur con-men that attempts to systematically change meek nerds into false-confident assholes.

"Why is that guy who usually wears videogame t-shirts and unkempt hygiene suddenly wearing douchey sunglasses indoors with a bad haircut and trying to insult every girl in here?"
"Oh him? He read a PUA book"

Abbreviation for either Potentially Unwanted Application Classification used by anti-malware software vendors for software which is not purely malicious like a computer virus or worm but performs undesirable activities such as tracking users or activities of questionable benefit, such as speeding up the system by an order of magnitude.

Alternately, might stand for Potentially Unsafe Application, a class of programs which perform legitimate activities in the hands of certain personnel, but can be abuse for malicious activity.

A program I downloaded was a PUA. It had an annoying toolbar in it and changed my browser's web search settings and home page.